Neuroscience Chapter 2

Neurons (nerve cells)

these communicate information between other neurons, glands, muscles and organs in the body

Glial cells

provide support for information processing neurons

Dendrites (input zone)

cellular extensions that receive information

Cell body (integration zone)

integrates and processes information

Axons (conduction zone)

carry information away from the cell body

Axon terminals (output zone)

transmit signals across synapses

most common type of neuron

multipolar (one axon many dendrites)

Motor neurons

stimulate muscles or glands

Sensory neurons

respond to environmental stimuli, such as light, odor, or touch

Interneurons

receive input from and send input to other neurons

Golgi stain shows

cell body and processes, but only stains a very small percentage of cells

Nissl stain shows

cell bodies only. Stains all cells

can be used to visualize cells that contain specific proteins, enzymes, etc

Immunocytochemistry

Tract tracing

chemicals are carried down axons to show where axons travel in the nervous system

Axonal transport

The movement of materials within an axon via motor proteins

Anterograde transport

The movement of substances from the cell body to the axon terminal

Retrograde transport

The movement of substances from the axon terminal to
the cell body

function of glial cells

support and enhance neurons

Astrocytes

many processes receive neuronal input and monitor activity

Microglial cells

small cells remove debris from injured cells

Myelination

glial cells wrap axons with a fatty sheath, myelin, to insulate and speed conduction

Multiple sclerosis

a demyelinating disease that causes an interruption in information flow down the axon

Schwann cells

form myelin sheath for cells outside the brain and spinal cord, such as in peripheral nerves

Oligodendrocytes

form myelin sheath in brain and spinal cord (but not in the peripheral nervous system)

Nodes of Ranvier

gaps between sections of myelin where the axon is exposed

Central nervous system (CNS)

the brain and spinal cord

Peripheral nervous system (PNS)

all parts of the nervous system found outside the skull and spinal column (ie, everything outside of the central NS)

Motor nerves

transmit information from the CNS to muscles, organs, and glands. A.K.A. Efferent Nerves

Efferent Nerves

transmit information from the CNS to muscles, organs, and glands

Sensory nerves

convey information from the body to the CNS. A.K.A. Afferent Nerves

Afferent Nerves

convey information from body to CNS

Somatic nervous system

connects brain and major muscles and sensory systems (voluntary)

Autonomic nervous system

Nerves that primarily control the viscera (organs) -- bodily functions you don’t normally have voluntary control over

Sympathetic nervous system

prepares the body for action

Parasympathetic nervous system

relax, rest and recover

Enteric nervous system

digestion/gut motility

two cerebral hemispheres of brain

cerebral cortex and folds

Cerebral cortex

folded outermost layer of the cerebral hemispheres, comprised mostly of neuron cell bodies, dendrites, and axons

Folds (gyri and sulci)

increase amount of cortex that can fit into the skull, and are grouped together into lobes

function of brain folds (gyri and sulci)

increase surface area

Gray matter

Contains more cell bodies and dendrites, which lack myelin

White matter

Consists mostly of axons with white myelin sheaths.

Basal ganglia (nuclei)

important in motor control; reciprocally connected with the cortex

Limbic system

includes structures important for learning and memory, cognitive functions, emotional regulation, sense of smell

the two distinct branches that fuse to form each spinal nerve

dorsal and ventral roots

Dorsal root

carries sensory information from the body to the spinal cord

Ventral root

carries motor information from the spinal cord to the muscles

Computerized axial tomography (CAT or CT)—

a measure of X-ray absorption at several positions around the head; maps tissue density

Magnetic resonance imaging (MRI)

produces high-resolution images using radio frequency energy

Diffusion tensor imaging (DTI)

uses MRI technology to study white matter tracts; based on fractional anisotropy (FA)

DTI tractography

uses mathematical manipulations to produce structural images of axonal fiber pathways

Positron emission tomography (PET)

produces images of brain activity: identifies brain regions that contribute to specific functions

Functional MRI (fMRI)

detects small changes in brain metabolism, such as oxygen use, in active brain areas

can show how networks of brain structures collaborate

fMRI